low pressure at vents

You probably don't have enough return to give your supply much air flow.

You may want to add a floor register return somewhere on the first floor. In an out of the way area.

As a test. Remove the blower return panel. Hold in the blower safety switch and have someone turn the thermostat to fan on, and check the air flow from the registers. then do the same test with the panel on. And see if its a lot less air. if so, add more return.

low pressure at vents

ok I just wanted to make sure Im going to be doing alot of work and I just want everything to be right. so 24x8 on the side with more vents and keep my existing 20x8 for the other side correct? and as far as the return maybe a 26x8 on the side with more vents, and leave the existing return on the side with less vents. thanks again

low pressure at vents

Is the side with less vents open to the other common areas?

Most of the time. When you count the number of returns to supplies. Even if the return number is the same as the number of supplies. The returns are using more restrictive grilles then the supplies. And you end up needing more returns.

low pressure at vents

the side with less vents is areas such as the laundry room, the kitchen, the living room and the dining room. I plan on adding a return in the dining room and in the laundry room. you said the return should be bigger than the supply, so should my return line be a 26x8? thanks alot everyone